Field
Various communication systems may benefit from load control. For example, systems that employ device-to-device (D2D) discovery signal transmissions may benefit from such load control.
Description of the Related Art
Device to device proximity detection is discussed in third generation partnership project (3GPP) documents including 3GPP RAN RP-122009 and technical report (TR) 36.843, which are each incorporated herein by reference in their entirety. Proximity detection can be based on a plurality of user equipment (UEs) transmitting and detecting discovery signals. In a so-called general use case, UEs are under the coverage of a cellular network. The network is assumed to assign an overall discovery resource pool. From this pool, UEs either are given or select in a contention based manner, a resource from the time and frequency multiplexed resources. A contention based approach, known as Type 1 discovery in TR 36.843, may be useful in order to support device-to-device (D2D) discovery for idle mode UEs. The discovery signals are conventionally assumed to be broadcasted. Therefore, there are no negative or positive acknowledgements from the receiving UEs. Accordingly, conventionally there is no way a transmitting device can know whether its discovery signal has collided with another device's signal. Therefore, a simple load controlling system where back-off time is applied after collision is not available.